[datatable-help] Unexpected behavior in setnames()

[Eduard Antonyan]

>
> I think if there is a `j` expression that computes on an .SD that has
> duplicated colnames, I think we just stop().


I'm not entirely sure what you mean by this. The following *should* work
imo:

    dt = data.table(x = 1:10, x = 10:1)

    dt[, lapply(.SD, sum)]


On Fri, Nov 8, 2013 at 2:56 PM, Steve Lianoglou <lianoglou.steve at gene.com>wrote:

> Right, agreed.
>
> On Fri, Nov 8, 2013 at 12:53 PM, Arunkumar Srinivasan
> <aragorn168b at gmail.com> wrote:
> > Sorry, forget the j-value. For `.SDcols`, even when we provide integers
> > (column numbers), internally, we compute the column name and subset to
> get
> > `.SD`. And this'll have to change.
> >
> > Arun
> >
> > On Friday, November 8, 2013 at 9:47 PM, Steve Lianoglou wrote:
> >
> > On Fri, Nov 8, 2013 at 12:45 PM, Arunkumar Srinivasan
> > <aragorn168b at gmail.com> wrote:
> >
> > Oh I can certainly agree with that. I guess we'll have to make some
> changes
> > to the code to use index based subsetting when .SDcols or j-value is
> number
> > then.
> >
> >
> > Not sure what you mean by j-value -- the examples you gave didn't
> > compute on the .SD, it just returned it.
> >
> > I think if there is a `j` expression that computes on an .SD that has
> > duplicated colnames, I think we just stop().
> >
> > Or did you mean something else?
> >
> > -steve
> >
> > On Friday, November 8, 2013 at 9:41 PM, Steve Lianoglou wrote:
> >
> > My gut reaction is:
> >
> > On Fri, Nov 8, 2013 at 12:37 PM, Arunkumar Srinivasan
> > <aragorn168b at gmail.com> wrote:
> >
> > Sure, here's an example of what I was trying to explain:
> >
> > Suppose:
> > DT <- data.table(x=1:5, y=1:5, x=6:10)
> >
> > Then,
> >
> > DT[, c(1,3), with=FALSE] # gives correct subset
> >
> >
> > This is "OK", we just do what the user asks, here, as they are being
> > very specific.
> >
> > DT[, c("x", "x"), with=FALSE] # gives column 1 twice - wrong
> >
> >
> > stop() -- we don't try to disambiguate (even if it "seems" specific)
> >
> > DT[, .SD, .SDcols=c("x", "x")] # gives column 1 twice - wrong result
> >
> >
> > stop()
> >
> > Also stop() on DT[, ..., .SDcols="x"]
> >
> > DT[, .SD, .SDcols=c(1,3)] # gives column 1 twice - wrong result - but
> >
> >
> > Do what the user asks for.
> >
> > No?
> >
> > -steve
> >
> > --
> > Steve Lianoglou
> > Computational Biologist
> > Bioinformatics and Computational Biology
> > Genentech
> >
> >
> >
> > _______________________________________________
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> > datatable-help at lists.r-forge.r-project.org
> >
> https://lists.r-forge.r-project.org/cgi-bin/mailman/listinfo/datatable-help
> >
> >
> >
> >
> > --
> > Steve Lianoglou
> > Computational Biologist
> > Bioinformatics and Computational Biology
> > Genentech
> >
> >
> >
> > _______________________________________________
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> > datatable-help at lists.r-forge.r-project.org
> >
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>
>
>
> --
> Steve Lianoglou
> Computational Biologist
> Bioinformatics and Computational Biology
> Genentech
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